Bearing arrangement for a feed bar of a sewing machine

ABSTRACT

A BEARING ARRANGEMENT FOR THE FEED BAR OF A SEWING MACHINE INCLUDING FRAME MEANS, THE FEED BAR HAVING OPPOSITE ENDS EACH HAVING AN AXIAL BORE HAVING A BOTTOM AND A CYLINDRICAL WALL SURFACE, THERE BEING A JOURNAL SPINDLE WITHIN EACH BORE, SUPPORTED BY THE FRAME MEANS, HAVING AN END SURFACE AND A GEOMETRICAL ENVELOPE SURFACE APPLIED AGAINST THE CYLINDRICAL WALL SURFACE OF THE   ASSOCIATED BORE AND A SPHERICAL BODY IS INTERPOSED BETWEEN THE BOTTOM OF EACH BORE AND THE END SURFACE OF THE ASSOCIATED SPINDLE, IF DESIRED, A HELICAL SPRING CAN BE INTERPOSED BETWEEN THE BOTTOM OF ONE BORE AND THE ASSOCIATED SPHERICAL BODY.

- P 1971 s. T. ROBERG 3,605,663

BEARING ARRANGEMENT FOR A FEED BAR OF A SEWING MACHINE Filed March 7, 1969 United States Patent 3,605,663 BEARING ARRANGEMENT FOR A FEED BAR OF A SEWING MACHINE Sven Theodor Roberg, Huskvarna, Sweden, assignor to Husqvarna Vapenfabriks Aktiebolag, Huskvarna, Sweden Filed Mar. 7, 1969, Ser. No. 805,186 Claims priority, application Sweden, Mar. 8, 1968, 3,077/ 68 Int. Cl. B65h 54/18 US. Cl. 112-218 6 Claims ABSTRACT OF THE DISCLOSURE A bearing arrangement for the feed bar of a sewing machine including frame means, the feed bar having opposite ends each having an axial bore having a bottom and a cylindrical wall surface, there being a journal spindle within each bore, supported by the frame means, having an end surface and a geometrical envelope surface applied against the cylindrical wall surface of the associated bore and a spherical body is interposed between the bottom of each bore and the end surface of the associated spindle; if desired, a helical spring can be interposed between the bottom of one bore and the associated spherical body.

This invention relates to bearing arrangements in sewing machines and in particular to bearing arrangements for feed bars in sewing machines in which the feed bar is provided at each end with an axial bore, in which a journal spindle, fitted in the sewing machine frame, is supported.

It is known to support the feed bar of a sewing machine by means of a pair of tail spindles or centre points which are fitted, adjustably in relation to one another, at a given distance apart in the sewing machine frame and are each inserted in its axial bore in the bar ends. The bearing surfaces between the spindles and the bores are conical so that the spindles can be applied against the bar ends and a bearing can thus be obtained in which there is no play. Because of wear and the settling down of the conical bearing surfaces by degrees it becomes necessary to reset the spindles as the bearing becomes worn. As a result of continuous resetting of the spindles in time the spindles become too diflicult to reset correctly, which causes the machine to run badly. Even when the spindles are fitted solidly, unequal expansion due to differential temperature rise in the frame and in the bar may cause defective seating of the bar.

It is an object of the present invention to provide a bearing arrangement where the security of the bar is obtained once and for all during the assembly of the machine without any stress due to adjustment. A certain degree of mobility is obtained due to the action of a spring, which is stressed as the journal spindle is fitted, which is an advantage, as the bearing is thereby automatically adjusted, following wear or any possible expansion due to temperature rise, in the frame in relation to the bar. It is sufiicient if the bearing at only one end of the bar is provided with a spring.

According to the invention there is provided a bearing arrangement for a feed bar of a sewing machine, which bar is provided at each end with an axial bore, in which bore there is supported a journal spindle fitted in the machine frame, characterized in that the geometric envelope surface of the spindle is applied against the cylindrical surface of the bore to retain the bar-end in the radial direction, and in that a spherical body is inserted between the bottom of the bore and the end surface of the journal 3,605,663 Patented Sept. 20, 1971 spindle and thereby retains the bar-end in the axial direction against the spindles.

In effecting the bearing of the other end the spring may advantageously be inserted between the spherical body and the bottom of the bore. The spherical bodies have at both ends very small surfaces of contact against adjacent bodies and receive only a slight torque in respect of same, the said torque being only slightly increased under increased axial loading.

A special embodiment of the invention will now be described in greater detail by way of example with reference to the accompanying drawing, wherein;

FIG. 1 represents a feed bar and its bearings partly in longitudinal section, and

FIG. 2 is a section along the line IIII in FIG. 1.

A pair of threaded journal spindles 3, 4 are screwed into tapped holes 5 and 6 in components 1 and 2 of the underpart of the sewing machine, where the feed bar is fitted. The feed bar 7 extends between and is rotatable about the journal spindles. The feed bar rotates with a reciprocating motion which is induced by a connecting member connecting a journal spindle 8, eccentrically fixed to the bar, to the drive members (not shown) of the sewing machine. A reciprocating motion is transmitted by a second connecting member 9, supported on a spindle 10, to the material feed device of the machine.

The bearing at each end of the feed bar comprises, as can be seen from the figure, at the end of the bar an axial bore 11, and a spherical body 12 which is placed between the spindles 3, 4 inserted in the bore and the bottom of the bore. The bearing surfaces between the spindles and the bore are the geometrical envelope surface 13 of the spindle and the cylindrical surface of the bore, and between the spherical body and the spindle at a point of application 14. In applying the body against the bottom of the bore, as shown at the left-hand end of the bar, the friction is such that the body is entrained by the rotary movement of the bar.

As can be seen from the figure, the spindles 3, 4 are screwed completely into the holes 5, 6 and are drawn up to that the heads of the spindles lie tightly against the components 1 and 2 respectively. The spindle 4 is screwed in against the action of a helical spring 15 which is applied by its ends against the bottom of the bore and the spherical body. The spring is stressed during the screwing-in of the spindle 4 and presses the bar to the left in the figure against the spindle 3. When the spindle 4 is completely screwed-in the bar is supported between the spindles, but because of the elasticity of the spring it is slightly movable in the axial direction. The effect of any wear between the spherical bodies and the spindles is thus obviated, because the spring lengthens accordingly.

The invention has there been described in a practical application to the feed bar for the upward and downward motion of the feed member. For the sake of clarity the bearing of the feed bar of a reciprocatingly-moving bar supported on the spindle in the bore 16 has been omitted from FIG. 1 but is shown in FIG. 2. The bearing of the feed bar is also effected in accordance with the invention by means of spring-loaded spherical bodies. Here with support of the two bars between the frame components 1 and 2 is independent of one another, and after-adjustments alternately of one and then the other bearing need not be effected.

Variants within the scope of the invention may be made in the form of embodiment just described. As can be seen from the drawing, the geometrical envelope surface at the end of the spindle may be made spherical. Such a form is advantageous if the bars are to be subjected to bending stresses. The spring need not be of the type shown, but may also be a leaf spring fitted on the outside of the component 2, and actuating a plain unscrewed spindle 3 axially movable in the hole 6. Furthermore the spherical body may take the form of a cylindrical rod with a spherical portion at one end.

What I claim is:

1. A bearing arrangement for a feed bar of a sewing machine including machine frame means, said feed bar having opposite ends each having an inwardly extending axial bore having a bottom and a cylindrical Wall surface, a journal spindle for each bore supported by said frame means and respectively within an axial bore, each journal spindle having an end surface and a geometric envelope surface applied against the cylindrical wall surface of the associated bore so as to retain the ends of said feed bar in the radial direction and a spherical body interposed between the bottom of each bore and the end surface of the associated journal spindle to retain the ends of said feed bar in the axial direction against said spindles,

2. A bearing arrangement for a feed bar of a sewing machine including machine frame means, said feed bar having opposite ends each having an inwardly extending axial bore having a bottom and a cylindrical Wall surface, a journal spindle for each bore supported by said frame means and respectively within an axial bore, each journal spindle having an end surface and a geometric envelope surface applied against the cylindrical wall surface of the associated bore, a spherical body in each bore between the bottom of each bore and the end surface of the associated journal spindle and a helical spring between the bottom of one bore and the associated cylindrical body.

3. A bearing arrangement as claimed in claim 1 and at least one journal spindle being axially movable relative to said frame means and a laminated spring fitted to said frame means and pressing said one journal spindle in the direction of said feed bar.

4. A bearing arrangement as claimed in claim 3 and the geometrical envelope surface of each journal spindle being spherical for at least a part of its length.

5. A bearing arrangement as claimed in claim 1 and the geometrical envelope surface of each journal spindle being spherical for at least part of its length.

6. A bearing arrangement as claimed in claim 2 and the geometrical envelope surface of each journal spindle being spherical for at least part of its length.

References Cited UNITED STATES PATENTS 2,858,089 10/1958 Yasui 112-218X 3,385,247 5/1968 Johnson et a1. 112218 PATRICK D. LAWSON, Primary Examiner 

